Saturday, July 29, 2017

The Illinois Department of Natural Resources is reintroducing a living fossil into its waterways. The alligator gar is a fish so old, it’s thought to have evolved during the Early Cretaceous period, more than a 100 million years ago.

Alligator gar are the second largest freshwater fish in North America. Illinois fisheries biologist Randy Sauer says they disappeared from the state’s waterways in the 1990s, although they continued to thrive in southern U.S. rivers.

“We want to restore the ecosystem because it is important to have top predators to balance the species below them in order to keep check on some more abundant species,” he said.

Beyond that, alligator gar make for great big game fishing. The diamond-scaled animals, which breathe both air and water, can grow up to 2.7 meters and weigh more than 136 kilograms. In fact, Sauer says, their large size is what did them in originally in the state.

“It was pretty much extirpated out of its range because of misconceptions about it eating sport fish,” he said. “People would target it and put bounties on it.”

Everything is on the menu

The alligator gar is an opportunistic feeder, meaning it will eat whatever it encounters — from an occasional turtle or small duck to invasive species such as Asian and silver carp. Sauer hopes the re-introduction program will help the state’s efforts to control the carp.

Because gar can live up to 60 years, this program is going to take decades to fully expand.

“The (female) alligator gar does not sexually mature until 11 years, and the male not till 6 or 7 years,” Sauer said, “so at the outset of this project we’re probably going to stock more heavily than 10 or 20 years down the road when hopefully these fish will find each other and start doing the job on their own.”

To date, 7,000 alligator gar fingerlings have been fitted with tiny transponder tags so that they can be tracked and then released into Illinois waterways. As it rains and floods, biologists expect some of the fish to follow the rivers all the way down to join other populations in Louisiana and Texas.